Iran's security forces have enjoyed a "climate of impunity" during six months of "sweeping repression" to put down mass protests, according to an Amnesty International report released Wednesday that catalogs abuses from rape, killings, torture, and show trials.

The Amnesty report is the most detailed accounting of abuses – and Iranian officials' attempts to cover them up – so far of the six months of political crisis in Iran.

Since disputed elections on June 12, Iran has been thrown into a political crisis as protesters – who at their peak numbered hundreds of thousands in the weeks after the vote – took to the streets to challenge what they called the fraudulent reelection of President Mahmoud Ahmadinejad.

"The authorities have resorted to exceptionally high levels of violence and arbitrary measures to stifle protest and dissent," notes the report. Instead of holding state agents accountable for crimes under Iran's penal code, Amnesty says, Iran's courts have been used "as part of a repressive state machinery to allow the security forces to act with impunity."

Iranian officials continue to deny that any of the more than 4,000 people arrested during the unrest were raped. After initial denials of any deaths in custody – and a number of contradictory statements on the issue – officials have since acknowledged three deaths at the Kahrizak detention facility, which was ordered closed in late July for being substandard.